brooklynwx99

Ripping here. The mixing line collapsed again after about 20 mins of sleet. The HRRR continues to advertise heavy snow over the metro until about 2-3 AM.

Okay, uh, holy crap. This is at 2AM too! Again, NYC remains just above the mix line, remaining in the area of highest snow intensity.

Wow. HUGE dendrites, +SN. This is just the beginning for the NYC metro, too. The high precipitation rates will also help to cool the column, limiting mixing. @Allsnow great visual indicating the mix line halting as a result.

02z HRRR is sick. The NYC metro doesn’t mix whatsoever with 0.75” additional LE. Also, these soundings continue to look insane. That’s a 2”+/hr look.

No, this is basically as good of a sounding as you can get. 2-3”/hr if it verified with possible thunder. That’s at JFK, too, which is a warmer part of NYC.

edit: again, for reasons i’ve gone over earlier, I don’t buy the mixing on the 3km NAM into the NYC metro given the immense lift and precipitation rates modeled.

The storm is really just beginning for the NYC metro. 850mb fgen is beginning to make its way into the NYC area, and snowfall rates are beginning to increase as a result. There is also strong LL convergence and UL divergence, which is indicative of intensifying precipitation. This will also make its way northward. I expect minimal mixing in the NYC region, if at all. The HRRR has been trending colder all day, and the initial snow at the onset of the storm indicates that the column may be colder than forecast. Overall, 6-10” for the NYC metro looks on line. 2” per hour rates aren’t out of the question, either.

All surfaces are now covered in Bay Ridge with about 0.5”. Let the games begin.

Steady light snow in Bay Ridge, Brooklyn. Even the colder HRDPS barely had rain into NYC, let alone steady snow.

I think that the 3km NAM’s depiction of rain into the NYC metro is incorrect. The 850mb temperatures are indicative of evaporational cooling given extremely high precipitation rates. 2m temperatures are slightly >0C, but that’s in a very small layer. This may be due to the 3km NAM’s convective parametrization, which would lead to an overestimation of latent heat release into the 700-800mb layer. This would lead to an overly warm look. There is also immense lift in the DGZ, which is further evidence for high precipitation rates. I will wait for the RGEM and HRDPS to see if my suspicions are confirmed. If they remain cold, then the NAM is most likely out to lunch regarding the liquid precipitation into the NYC metro.

I’m sticking with my call from yesterday. 6-10” for the NYC metro. 6-8” reports will be more widespread with a few reports approaching 10”.

The RGEM is absolutely nuclear. Crush job for NYC and surrounding areas.

ITT: conversations about sea ice and geography when an impending low-end MECS will hit the most populated area on the EC in less than 48 hours

Yes, I am. I was waiting to see if the 18z RGEM/HRDPS held serve, and since they did, I am rather confident in a 6-10" event for the NYC metro. To be more specific, I would say 6-8" generally with some 8-10" reports. I believe that the hi-res Canadian suite has a better handle on temperature profiles and precipitation distribution/strength. For example, the RGEM has snow into coastal C NJ at hour 34, which makes sense given 850mb temperatures <0C, 2m temperatures at 32-34, and NNE 2m winds. However, the 18z 3km NAM has sleet into NYC at the same hour given nearly identical temperature and wind profiles (the NAM is actually colder at 850mb!). This might be due to lower precipitation rates or a small warm layer around 750mb, but I doubt a warm push that strong at that height given the LP track. Also, there will be considerable low level fgen, which will lead to prolific precipitation rates in areas on the coastal plain. Overall, I stand with my forecast. I expect the ECMWF to trend slightly colder to fall in line with other guidance, but I expect the RGEM to prevail, as it is rather deadly inside of 36 hours. I'm very curious to see if the HRDPS remains in step with its slightly lower-res counterpart, as well.